Image forming apparatus

Abstract

An image forming apparatus includes a sheet conveyance section configured to convey a long sheet; an image forming section configured to transfer a toner image to a long sheet; and a fixing section configured to apply heat and pressure to a long sheet conveyed along a sheet feeding path at a fixing nip so as to fix a toner image. During cooling-down or warming-up of the fixing section, the sheet conveyance section performs conveyance of a long sheet when the a fixing temperature of the fixing side member is higher than a predetermined idling temperature, and stops conveyance of a long sheet when the fixing temperature of the fixing side member is lower than the predetermined idling temperature.

What is claimed is: 
     
       1. An image forming apparatus for use with a long sheet, the image forming apparatus comprising:
 a sheet conveyance section configured to convey the long sheet; 
 an image forming section configured to transfer a toner image to the long sheet; and 
 a fixing section comprising a fixing side member configured to make contact with a fixing surface of the long sheet, a back side supporting member configured to be brought into pressure contact with the fixing side member so as to form a fixing nip, and a heating section configured to apply heat to the fixing side member, the fixing section being configured to apply heat and pressure to the long sheet conveyed along a sheet feeding path at the fixing nip so as to fix the toner image wherein, 
 the sheet conveyance section is configured such that, during cooling-down or warming-up of the fixing section, the sheet conveyance section performs conveyance of the long sheet when a temperature of the fixing side member is higher than a predetermined idling temperature, the idling temperature being a temperature at which discoloration and deformation of the long sheet are not caused even when conveyance of the long sheet is stopped, and stops conveyance of the long sheet when the temperature of the fixing side member is lower than the predetermined idling temperature. 
 
     
     
       2. The image forming apparatus according to  claim 1 , wherein, after an end position of the toner image passes through the fixing section during the cooling-down of the fixing section, the sheet conveyance section sets a conveyance speed of the long sheet to a speed lower than a conveyance speed for image formation. 
     
     
       3. The image forming apparatus according to  claim 1  further comprising a cooling section configured to cool down the fixing side member or the back side supporting member after an end position of the toner image passes through the fixing section during the cooling-down of the fixing section. 
     
     
       4. The image forming apparatus according to  claim 1  further comprising a pressure contact separation section configured to bring the fixing side member and the back side supporting member into pressure contact with each other, or separate the fixing side member and the back side supporting member from each other, wherein,
 during the cooling-down of the fixing section, the pressure contact separation section maintains a pressure contact state between the fixing side member and the back side supporting member until the temperature of the fixing side member reaches the predetermined idling temperature, and separates the fixing side member and the back side supporting member from each other after the temperature of the fixing side member reaches the predetermined idling temperature. 
 
     
     
       5. The image forming apparatus according to  claim 1 , wherein, during the warming-up of the fixing section, the sheet conveyance section sets a conveyance speed of the long sheet to a speed lower than a conveyance speed for image formation until the temperature of the fixing section reaches a predetermined fixable temperature. 
     
     
       6. The image forming apparatus according to  claim 1  further comprising a pressure contact separation section configured to bring the fixing side member and the back side supporting member into pressure contact with each other, or separate the fixing side member and the back side supporting member from each other, wherein,
 during the warming-up of the fixing section, the pressure contact separation section maintains a separation state between the fixing side member and the back side supporting member until the temperature of the fixing side member reaches a predetermined fixable temperature, and bring the fixing side member and the back side supporting member into pressure contact with each other after the temperature of the fixing side member reaches the predetermined fixable temperature. 
 
     
     
       7. The image forming apparatus according to  claim 1 , wherein the predetermined idling temperature is set in accordance with a sheet type.